title: Sheep tissue acetyl coenzyme A-dependent arylamine N-acetyltransferases.
abstract: Acetyl coenzyme A-dependent arylamine N-acetyltransferases (NATs), EC 2.3.1.5. were measured in sheep tissues (N = 14) using p-aminobenzoic acid (PABA) as a substrate. Specific activities of liver, kidney, and lung NATs were 5.3 x 10(-3) +/- 1.4 (mean +/- SE) nmoles.min-1.mg protein-1, 3.4 x 10(-3) +/- 1.1 nmoles.min-1.mg protein-1, 2.5 x 10(-3) +/- 1.2 nmoles.min-1.mg protein-1, respectively. Km values were 53 +/- 3 microM for liver, 34 +/- 2 microM for kidney, and 28 +/- 2 microM for lung tissue. Optimum pH for the acetylation reaction was found as 7.5. The enzyme activity was stable for at least 6 months in all tissues, when stored at -70 degrees C. The enzyme from sheep tissues were quite heat-stable. Inhibition studies showed that N-ethylmaleimide was a potent inhibitor of sheep tissue NAT enzymes.
authors.affiliation: Department of Biological Sciences, Middle East Technical University, Ankara, Turkey.
authors.forename: T
authors.initials: T
authors.lastname: Guray
authors.forename: T
authors.initials: T
authors.lastname: Guvenc
mesh_terms: D010129:4-Aminobenzoic Acid / Q000378:metabolism; D000105:Acetyl Coenzyme A / Q000378:metabolism*; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D005033:Ethylmaleimide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008168:Lung / Q000201:enzymology*; D012756:Sheep; D013696:Temperature
chemical_list: D004791:Enzyme Inhibitors; D000105:Acetyl Coenzyme A; D001191:Arylamine N-Acetyltransferase; D005033:Ethylmaleimide; D010129:4-Aminobenzoic Acid